Mode Of Reproduction Research Articles

Exploring the protective role of jelly capsules in jelly‐nest tree frog eggs based on proteomic and peptidomic studies

AbstractTypically, frog eggs are aquatic, being deposited and undergoing development within freshwater habitats. However, certain species within the Rhacophoridae have evolved reproductive modes that are non‐aquatic. The jelly‐nest tree frog (Feihyla palpebralis) has terrestrial eggs that are enclosed in gel, with embryos detaching from the aquatic milieu during the embryonic phase. The jelly enveloping these embryos performs a critical role in defense against biotic and abiotic threats in the terrestrial environment. To investigate the protective function of the jelly, we characterized its proteome and peptidome. In total, 83 proteins were identified and categorized into eight main groups: protease inhibitors, glycoproteins, cytoskeleton proteins, nucleotide‐binding proteins, regulatory proteins, metabolic enzyme, glycoprotein hormones, and oxidative stress‐related proteins. These proteins are believed to play a role in protecting the eggs by creating biochemical and physical barriers, maintaining moisture and structural integrity, and preventing oxidative damage. In addition, 1642 peptides were isolated from tree frog jelly envelopes. Among these, RPPGFSPFR showed predator deterrent properties, LPF and AVPYPQ performed anti‐inflammatory and antioxidant activities, and IYSP functioned as a proteinase inhibitor. These findings help to clarify the protective mechanisms involved in the egg development process of the jelly‐nest tree frog.

Mitogenome of a new Ramazzottius species (Tardigrada: Eutardigrada: Ramazzottiidae) discovered in rock pools along with its temperature and desiccation-related proteins repertoire

AbstractRamazzottius is a widespread genus of tardigrades with extreme cryptobiotic capabilities. Thanks to its ability to survive desiccation and freezing, this genus is usually recorded from harsh habitats such as exposed mosses and lichens and rock pools. In the last years, research focused on both describing Ramazzottius diversity and revealing the molecular mechanisms behind their cryptobiotic capabilities. Despite the research efforts in these fields, much still remains to be discovered. Here we describe a new Ramazzottius species from an Italian rock pool by means of integrative taxonomy (morphology, morphometry, and DNA sequencing) and sequenced its genome with Nanopore technology to provide an assembled mitogenome and annotate its Temperature and Desiccation Resistance Proteins (TDPR) repertoire. The new gonochoric species is phylogenetically close to the parthenogenetic R. varieornatus, a strain of which (YOKOZUNA-1) has been adopted as model organism for the study of cryptobiosis. The mitogenome of the new species shows perfect synteny with R. varieornatus and shares with it most of the TDPR genes. The relative genetic similarity of the new species to the model R. varieornatus, combined with unique biological traits (for example the difference in reproductive mode and the unique habitat it colonizes), makes the new species a potential new addition to the range of model tardigrade species.

Population genetics of the freshwater red alga Batrachospermum gelatinosum (Rhodophyta) II: Phylogeographic analyses reveal spatial genetic structure among and within five major drainage basins in eastern North America.

The freshwater red alga Batrachospermum gelatinosum has a well-documented distribution spanning historically glaciated and unglaciated eastern North America. This alga has no known desiccation-resistant propagule; thus, long-distance dispersal events are likely rare. We predicted strong genetic structure among drainage basins and admixture among sites within basins. We predicted greater genetic diversity at lower latitude sites because they likely serve as refugia and the origin of northward, post-Pleistocene range expansion. We used 10 microsatellite loci to investigate genetic diversity from 311 gametophytes from 18 sites in five major drainage basins: South Atlantic Gulf, Mid-Atlantic, Ohio River, Great Lakes, and Northeast. Our data showed strong genetic partitioning among drainage basins and among sites within basins, yet no isolation by distance was detected. Genetic diversity varied widely among sites and was not strictly related to latitude as predicted. The results from B. gelatinosum provide strong support that each stream site contributes to the unique genetic variation within the species, potentially due to limited dispersal and the prevailing reproductive mode of intragametophytic selfing. Simulations of migration suggested post-Pleistocene dispersal from the Mid-Atlantic. Batrachospermum gelatinosum potentially persisted in refugia that were just south of the ice margins rather than in the southernmost part of its range. Research of other taxa with similar ranges could determine whether these results are generally applicable for freshwater red algae. Nevertheless, these results from B. gelatinosum add to the growing literature focused on the patterns and genetic consequences of post-Pleistocene range expansion by eastern North American biota.

An Effective Method for Reproducing the Flow of a Gas-Liquid Mixture Using a Flow Standard

The appearance on the market of measuring equipment of multiphase flowmeters used in the oil and gas industry to measure the amount of extracted hydrocarbons directly at wells without preliminary separation and performing the function of operational accounting raised the question of their metrological support in accordance with the requirements of regulatory documents of the sphere of state regulation in this field of measurements. His decision was to create a reference base, the basis of which was the State primary special standard for units of mass flow of gas-liquid mixtures GET 195-2011 and a verification scheme for measuring multiphase flow rates, regulated by GOST 8.637-2013. When transmitting units of volume and mass flow of a multiphase mixture with the required accuracy, the main problem is the difficulty of reproducing and maintaining stability of several flow parameters at once – mass flow and content of liquid components (water and oil simulator) and volume flow of the gas phase. It should also be borne in mind that test programs for the purpose of approving the type of multiphase flow measuring instruments, as well as verification and calibration methods, provide for changing the modes of reproduction of a gas-liquid mixture, covering the measurement ranges of multiphase flowmeters. Such standards used in practice represent a very complex measuring system consisting of storage tanks for components, supply pumping and compressor units, control equipment, mixers and separators, measuring instruments for the physical parameters of multiphase flow components and an automated control system. Given the high cost of multiphase standards, when creating them, effective methods and methods should be used to reproduce the flow of a multiphase mixture with specified parameters, as well as to make a fairly rapid transition to the next mode provided by the program or methodology, which will reduce the time and production costs for the procedure of transferring units of measurement from the standard to the working measuring instrument. This article describes a method for reproducing the flow rate of a gas-liquid mixture according to the original technological scheme introduced during the development of the 1st category standard. Constructive solutions are presented that increase the efficiency of the liquid component separation apparatus to increase the dosing accuracy, as well as expand the range of reproduction of the flow rate and parameters of the multiphase flow, ensuring the consistency of the composition of the liquid mixture at a given regime. An original rational method of compressing and maintaining the pressure of the gas phase is described, which allows you to quickly switch to the next mode, confirmed by the results of experimental studies of the standard.

New insights into transcriptional and metabolic differences between pregnant males and embryos in seahorses

Seahorses exhibit a unique reproduction mode of male pregnancy. Successful gestation plays a crucial role in the seahorse reproduction process and the aquaculture industry. However, the substantial paternal-embryo differences in seahorses remain largely unexplored. In the present study, transcriptomic and metabolic differences between pregnant males and embryos during gestation were explored to investigate the roles of key genes and metabolites in pregnant males and embryos in seahorses. Higher levels of essential amino acids and polyunsaturated fatty acids in embryos compared to fathers may indicate their vital role in embryonic development. The high expression of immune-related genes (CCLs and CCRs) and downregulation of antioxidants in fathers may provide immune protection and reduce the immunological rejection of embryos during gestation. The transcript-metabolite correlation network during pregnancy further indicated the role of key genes and metabolites during embryonic eye (N-acetyl-L-histidine, PAX6, and FZT4) and tail (WNT5 and WNT8) development. The findings of the present study not only provide valuable data on differences between pregnant males and embryos in seahorse, but also lay foundation for future research on seahorse aquaculture.

The extension of mammalian pregnancy required taming inflammation: Independent evolution of extended placentation in the tammar wallaby.

In the first live-bearing mammals, pregnancy was likely short and ended with a brief period of inflammatory maternal-fetal interaction. This mode of reproduction has been retained in many marsupials. While inflammation is key to successful implantation in eutherians, a key innovation in eutherians is the ability to switch off this inflammation after it has been initiated. This extended period, in which inflammation is suppressed, likely allowed for an extended period of placentation. Extended placentation has evolved independently in one lineage of marsupials, the macropodids (wallabies and kangaroos), with placentation lasting beyond the 2 to 4 d seen in other marsupial taxa, which allows us to investigate the role of inflammation response after attachment in the extension of placentation in mammals. By comparing gene expression changes at attachment in three marsupial species, the tammar wallaby, opossum, and fat-tailed dunnart, we show that inflammatory attachment is an ancestral feature of marsupial implantation. In contrast to eutherians, where attachment-related (quasi-) inflammatory reaction is even involved in epitheliochorial placentation (e.g., pig), this study found no evidence of a distinct attachment-related reaction in wallabies. Instead, only a small number of inflammatory genes are expressed at distinct points of gestation, including IL6 before attachment, LIF throughout placentation, and prostaglandins before birth. During parturition, a more distinct inflammatory reaction is detectable, likely involved in precipitating the parturition cascade similar to eutherians. We suggest that in wallaby, extended gestation became possible by avoiding an inflammatory attachment reaction, which is a different strategy than seen in eutherians.

The Amphibian Genomics Consortium: advancing genomic and genetic resources for amphibian research and conservation.

Amphibians represent a diverse group of tetrapods, marked by deep divergence times between their three systematic orders and families. Studying amphibian biology through the genomics lens increases our understanding of the features of this animal class and that of other terrestrial vertebrates. The need for amphibian genomic resources is more urgent than ever due to the increasing threats to this group. Amphibians are one of the most imperiled taxonomic groups, with approximately 41% of species threatened with extinction due to habitat loss, changes in land use patterns, disease, climate change, and their synergistic effects. Amphibian genomic resources have provided a better understanding of ontogenetic diversity, tissue regeneration, diverse life history and reproductive modes, antipredator strategies, and resilience and adaptive responses. They also serve as essential models for studying broad genomic traits, such as evolutionary genome expansions and contractions, as they exhibit the widest range of genome sizes among all animal taxa and possess multiple mechanisms of genetic sex determination. Despite these features, genome sequencing of amphibians has significantly lagged behind that of other vertebrates, primarily due to the challenges of assembling their large, repeat-rich genomes and the relative lack of societal support. The emergence of long-read sequencing technologies, combined with advanced molecular and computational techniques that improve scaffolding and reduce computational workloads, is now making it possible to address some of these challenges. To promote and accelerate the production and use of amphibian genomics research through international coordination and collaboration, we launched the Amphibian Genomics Consortium (AGC, https://mvs.unimelb.edu.au/amphibian-genomics-consortium) in early 2023. This burgeoning community already has more than 282 members from 41 countries. The AGC aims to leverage the diverse capabilities of its members to advance genomic resources for amphibians and bridge the implementation gap between biologists, bioinformaticians, and conservation practitioners. Here we evaluate the state of the field of amphibian genomics, highlight previous studies, present challenges to overcome, and call on the research and conservation communities to unite as part of the AGC to enable amphibian genomics research to "leap" to the next level.

Functional traits and ecosystem implications in the Multiple Use Marine Protected Area Almirantazgo Sound: A baseline study of scallop banks and benthic communities

Amid escalating environmental challenges confronting marine ecosystems, the proliferation of coastal and marine protected areas (MPAs) has emerged as a pivotal strategy for mitigating biodiversity loss and fostering sustainable resource management. This research advocates for a paradigm shift towards a trait-based approach to assess functional diversity (FD) within MPAs, with a specific focus on the ecologically crucial Austrochlamys natans banks in Parry Bay, MPA Almirantazgo Sound. By surveying 28 invertebrate species across eight phyla, a PCA using fuzzy-coded functional traits revealed five distinct groupings primarily based on feeding, movement, and reproductive modes. Mobile predators and scavengers clustered distinctly from sessile suspension feeders and limited-mobility grazers, indicating a scarcity of mobile predator species in Parry Bay, which impacts the ecosystem's dynamics. FD indices highlighted low functional α-diversity, emphasizing trait redundancy that enhances resilience but relies heavily on a few unique and specialized species. The potential extinction or migration of these species could directly affect unique ecosystem properties. While revealing the resilience of the benthic community, this research underscores its dependence on a handful of species that are crucial for both ecological functions and regional commercial significance. Urgent conservation and management measures are imperative to protect these species and maintain the delicate balance of this ecosystem.

Population distribution characteristics of mating type genes and genetic stability in Morchella sextelata.

The reproductive mode of morels (Morchella spp.) is governed by mating type genes, specifically MAT1-1 and MAT1-2. This study investigated the presence of mating type genes at various growth stages and in different parts of cultivated Morchella sextelata. This study revealed significant fluctuations in the detection ratio of the two mating type genes during ascocarps growth. Single ascospore strains with MAT1-1, MAT1-2 and both mating types were selected for experimentations. Stress stimuli including H2O2, Congo red and NaCl were introduced into the medium. Differences in the cultural and physiological characteristics of single spore strains were analyzed, and mating type genes were identified after subculturing to assess their stability. The results indicated that a total of 297 samples with a single mating type gene were detected in 480 samples selected from the five stages of fruiting body growth, accounting for 61.9%. Stress exposure influenced colony morphology, mycelial growth rate, and biomass, leading to significant increases in malondialdehyde content and osmotic adjustment compounds, including soluble protein and proline. Physiological and biochemical parameters varied among the three mating type strains under different stress conditions. Principal component analysis was used to calculate the weight values, which showed that the MAT1-2 strain exhibited the highest tolerance to chemical stresses, particularly oxidative stress. Subculturing under stress revealed that single mating type strains ceased growth by the 8th generation, whereas both mating type strains could continue to the 15th generation without loss of mating type genes, indicating broader environmental adaptability and higher viability. These findings offer novel insights into mating type gene function and serve as a scientific foundation for the development of high-yield, stress-resistant morel varieties.

Parental care of underwater egg clutches in Andean water frogs (Anura: Telmatobiidae)

The most generalized reproductive mode in anurans is the deposition of egg clutches in water that develop into exotrophic aquatic tadpoles. Yet, despite this extended distribution, cases of parental care on submerged egg clutches are poorly documented. Because of its high diversity, its aquatic habits, and reports on males of two species standing next to the clutch, the Andean genus Telmatobius Wiegmann, 1834 offers an excellent model to examine the evolution of such behavior and the factors influencing it. Here, we combine field and laboratory studies to describe the breeding biology and parental care behavior on Telmatobius culeus (Garman, 1876), Telmatobius hintoni Parker, 1940, Telmatobius intermedius Vellard, 1951, Telmatobius jelskii (Peters, 1873), and Telmatobius oxycephalus Vellard, 1946. Our findings indicate that these five species have prolonged breeding season, and use concealed underwater shelters between rocks or macrophytes for mating and egg deposition. We showed that clutches of 35–560 eggs are deposited in these shelters. Males were observed next to the egg clutch and defending it aggressively against intruders, including conspecifics. Females were, on average, larger than males supporting the hypothesis that competition among males does not drive sexual size dimorphism in the genus. Our findings provide meaningful data to use in conservation programs, given that most species of Telmatobius are considered endangered and fill a significant information gap in understanding parental care’s origin in Nobleobatrachia.

A synthetic review: natural history of amniote reproductive modes in light of comparative evolutionary genomics

ABSTRACTThere is a current lack of consensus on whether the ancestral parity mode was oviparity (egg‐laying) or viviparity (live‐birth) in amniotes and particularly in squamates (snakes, lizards, and amphisbaenids). How transitions between parity modes occur at the genomic level has primary importance for how science conceptualises the origin of amniotes, and highly variable parity modes in Squamata. Synthesising literature from medicine, poultry science, reproductive biology, and evolutionary biology, I review the genomics and physiology of five broad processes (here termed the ‘Main Five’) expected to change during transitions between parity modes: eggshell formation, embryonic retention, placentation, calcium transport, and maternal–fetal immune dynamics. Throughout, I offer alternative perspectives and testable hypotheses regarding proximate causes of parity mode evolution in amniotes and squamates. If viviparity did evolve early in the history of lepidosaurs, I offer the nucleation site hypothesis as a proximate explanation. The framework of this hypothesis can be extended to amniotes to infer their ancestral state. I also provide a mechanism and hypothesis on how squamates may transition from viviparity to oviparity and make predictions about the directionality of transitions in three species. After considering evidence for differing perspectives on amniote origins, I offer a framework that unifies (i) the extended embryonic retention model and (ii) the traditional model which describes the amniote egg as an adaptation to the terrestrial environment. Additionally, this review contextualises the origin of amniotes and parity mode evolution within Medawar's paradigm. Medawar posited that pregnancy could be supported by immunosuppression, inertness, evasion, or immunological barriers. I demonstrate that this does not support gestation or gravidity across most amniotes but may be an adequate paradigm to explain how the first amniote tolerated internal fertilization and delayed egg deposition. In this context, the eggshell can be thought of as an immunological barrier. If serving as a barrier underpins the origin of the amniote eggshell, there should be evidence that oviparous gravidity can be met with a lack of immunological responses in utero. Rare examples of two species that differentially express very few genes during gravidity, suggestive of an absent immunological reaction to oviparous gravidity, are two skinks Lampropholis guichenoti and Lerista bougainvillii. These species may serve as good models for the original amniote egg. Overall, this review grounds itself in the historical literature while offering a modern perspective on the origin of amniotes. I encourage the scientific community to utilise this review as a resource in evolutionary and comparative genomics studies, embrace the complexity of the system, and thoughtfully consider the frameworks proposed.

Exploring the Arsenal of Novel Antifungal Drug Targets for Combating Fungal Infections.

Fungal infections contribute to over 1.5 million fatalities each year, with cutaneous mycoses standing as prominent global infections. The spectrum of these mycoses varies widely, encompassing enduring afflictions like ringworm, localized infections such as tinea capitis, recurrent instances like vaginal candidiasis, and potentially fatal systemic infections impacting multiple organ systems. The escalating recognition of the health and socioeconomic ramifications associated with fungal pathogens underscores their importance in contemporary discourse. On a global scale, projections indicate that over 300 million individuals experience significant fungal infections annually, resulting in a mortality rate exceeding 1.5 million deaths per year. Alarmingly, resistance to commonly used antifungal drugs was on the rise, with some reports suggesting that over 10% of Candida bloodstream isolates worldwide were resistant to fluconazole, a commonly prescribed antifungal medication. Therefore, there is an immediate need to increase the accessibility of new antifungal medications while minimizing their costs and adverse effects. Fungi, as heterotrophic organisms, acquire nutrients through absorption. Their filamentous structure, composed of hyphae, facilitates efficient nutrient uptake by secreting enzymes that break down complex organic matter into simpler compounds. These organisms exhibit remarkable adaptability in responding to environmental cues, adjusting growth rates, and altering morphological features. Fungi regulate their metabolism intricately, undergoing various metabolic pathways for energy production and utilizing diverse substrates for respiration. Additionally, they exhibit distinctive reproductive strategies, employing both sexual and asexual modes of reproduction, contributing to their genetic diversity and resilience in diverse ecosystems. We now have more information than ever on the origins of infection as well as the physiology of fungi cells, giving us the chance to use it to produce new generations of antifungals. This review includes various novel antifungal drug targets showing their possible effects via different mechanisms aiming at vital functions like GPI synthesis, cell wall synthesis, hyphal growth, and other essential pathways responsible for fungal growth.

Mating system, morphological and genetic evidence endorse clonality as an essential reproductive mode in Daphnopsis filipedunculata (Thymelaeaceae), a dioecious and endemic species from the Amazon.

Background and Aims: Clonality is characterized by the formation of independent individuals of the same genotype that are capable of reproducing and propagating vegetatively. Although clonality is an important mechanism that facilitates the persistence of a population, its extensive use can lead to negative impacts on sexual reproduction due to trade-offs in the investment of resources. Therefore, studies on the sexual reproduction of species that exhibit clonality can provide information about resilience to environmental changes, information about fecundity, the risk of the absence of pollinators and the ability to persist in unfavourable conditions and to successfully occupy new areas. Here, we investigated the role of clonal propagation and sexual reproduction in Daphnopsis filipedunculata (Thymelaeaceae), a dioecious species distributed only in Serra dos Carajás. Methods: We evaluated the extent of clonality in this species using molecular tools and anatomical analyses of the underground system responsible for developing new ramets. Furthermore, we analysed the sexual system and its contribution to reproductive success through morphometric analyses of floral types and pollination experiments in the field. Key Results: Overall, we found that clonal propagation plays an important role in maintaining the population of D. filipedunculata. Specifically, we demonstrated that this species presents functional male and female plants, indicating that D. filipedunculata is an obligate xenogamous species but has low reproductive success. We also showed that clonal vegetative propagation is the main form of asexual reproduction in this species, with roots responsible for clonal growth. Finally, our results indicated that this species presents an intermediate phalanx-guerrilla clonal architecture. Conclusions: Our study provides the first insights into sexual reproduction and clonal propagation in D. filipedunculata and can inform management practices, conservation and the restoration of endemic species.

The evolution of reproductive characters: an organismal-relational approach

This paper delves into the character concept as applied to reproduction. Our argument is that the prevailing functional-adaptationist perspective falls short in explaining the evolution of reproductive traits, and we propose an alternative organismal-relational approach that incorporates the developmental and interactive aspects of reproduction. To begin, we define the functional individuation of reproductive traits as evolutionary strategies aimed at enhancing fitness, and we demonstrate how this perspective influences the classification of reproductive characters and modes, the comprehension of shared traits as resulting from conflicts of evolutionary interest between individuals, and the explanation of reproductive diversity. After outlining the shortcomings of this framework, we introduce an organismal-relational approach grounded in evolutionary developmental studies of reproduction. This view provides a revised classification for reproductive characters and modes and offers a new understanding of interorganismal traits that takes into account their inherently relational nature. Lastly, we present the research agenda that emerges from this approach, which addresses the core explanatory gaps left by the adaptationist perspective, including the explanation of reproductive homologies and homoplasies, the developmental constraints associated with the evolution of reproductive modes, and the evolvability of reproductive characters.

Reproductive futures within a context of uterus transplants in India.

Reproduction is considered a core event in a cisgender heterosexual woman's life. Several hierarchies exist within the field of reproduction, with reproduction being privileged among people from dominant races, classes, castes, ages, and abilities. In this paper, I explore uterine transplantion as an emerging mode of reproduction, which privileges the experience of pregnancy in addition to genetic relatedness, specifically within the Indian context. The focus is on the socio-cultural and economic discourses surrounding the marketisation of reproductive technologies and how these recalibrate social and familial dynamics concerning reproduction. I argue that the mobilisation of the language of reproduction as a right could potentially transform into reproduction as a duty. Reproductive biopolitics is used as a lens to think through the value of wombs in relation to the bodies they inhabit, and the pressures the marketisation of wombs puts on both recipients and donors.

Reproductive modes in populations of late-acting self-incompatible and self-compatible polyploid Ludwigia grandiflora subsp. hexapetala in western Europe

Reproductive modes in populations of late-acting self-incompatible and self-compatible polyploid Ludwigia grandiflora subsp. hexapetala in western Europe

Asexuality shapes traits in a hybrid fish

Animal morphology is influenced by several factors, including gonadal development and gametogenesis. Although their effects are well documented in male/female differentiation, much less is known about same-sex effects, such as those caused by their mode of reproduction. Here, using geometric morphometric analyses, we compare two groups of all-female triploid hybrid fish Chrosomus eos × eos-neogaeus, that differ only by their sexual and asexual reproductive strategies. We demonstrate that morphological differences arise from factors inherently associated with their mode of reproduction, with results replicated in two distinct lineages and in natural and common garden environments. Such differences provide additional insight about the costs and benefits of both reproductive strategies, which have mostly been of a demographic, population genetic, or genetic nature. In particular, these findings have important implications for the ecology of asexual organisms and contribute to the study of sex evolution by adding complexity to the paradox of sex theory.

Earthworm (Oligochaeta, Lumbricidae) intraspecific genetic variation and polyploidy.

Earthworms are known for their intricate systematics and a diverse range of reproduction modes, including outcrossing, self-fertilization, parthenogenesis, and some other modes, which can occasionally coexist in a single species. Moreover, they exhibit considerable intraspecific karyotype diversity, with ploidy levels varying from di- to decaploid, as well as high genetic variation. In some cases, a single species may exhibit significant morphological variation, contain several races of different ploidy, and harbor multiple genetic lineages that display significant divergence in both nuclear and mitochondrial DNA. However, the relationship between ploidy races and genetic lineages in earthworms remains largely unexplored. To address this question, we conducted a comprehensive review of available data on earthworm genetic diversity and karyotypes. Our analysis revealed that in many cases, a single genetic lineage appears to encompass populations with different ploidy levels, indicating recent polyploidization. On the other hand, some other cases like Octolasion tyrtaeum and Dendrobaena schmidti/D. tellermanica demonstrate pronounced genetic boundaries between ploidy races, implying that they diverged long ago. Certain cases like the Eisenia nordenskioldi complex represent a complex picture with ancient divergence between lineages and both ancient and recent polyploidization. The comparison of phylogenetic and cytological data suggests that some ploidy races have arisen independently multiple times, which supports the early findings by T.S. Vsevolodova-Perel and T.V. Malinina. The key to such a complex picture is probably the plasticity of reproductive modes in earthworms, which encompass diverse modes of sexual and asexual reproduction; also, it has been demonstrated that even high-ploidy forms can retain amphimixis.

Remodeling of Uterine Tissues During Gestation of Potamotrygon wallacei (Elasmobranchii), a Neotropical Freshwater Stingray Endemic to the Negro River, Central Amazonia.

Neotropical freshwater stingrays of the subfamily Potamotrygoninae exhibit aplacental viviparity with uterine trophonemata. In this reproductive mode, females nourish and provide oxygenation to the embryo via the mucosa of the uterine wall. The aim of this study was to describe and histologically quantify the tissue components of the gravid uterus in an Amazonian freshwater stingray. Adult females of Potamotrygon wallacei were studied in different reproductive periods: resting stage, pregnant, and postpartum. During reproductive rest, the left ovary has numerous follicles compared to the right side. Therefore, uterine fertility is usually higher on the left side. The presence of an embryo in the right uterus suggests that the right ovary is also functional, although this only occurs in larger females. In females at reproductive rest, the wall of the uterus is formed by a mucosal layer (without the trophonemata) that contributes 16.7% to the thickness, while the myometrium accounts for 83.3% of the thickness. The mass-specific volume of the mucosal layer, inner circular, and outer longitudinal smooth muscle sheets tend to increase in the gravid uterus, indicating hypertrophy and hyperplasia of these components. During pregnancy, the trophonemata undergo marked tissue remodeling. Epithelial cells are organized into glandular acini and have apical secretory vesicles; furthermore, peripheral blood vessels proliferate and become dilated. These characteristics demonstrate that the gravid uterus of P. wallacei presents intense uterolactation activity and provides oxygenation to the fetus. Tissue remodeling occurs only in the uterus with the presence of an embryo. During postpartum, females have low body condition factor indicating a high reproductive cost. This study contributes to the knowledge of the reproductive biology of this species and will help us understand the impacts of climate change on the breeding areas of potamotrygonids.

Gastrotheca Fitzinger, 1843 tadpole morphology: Larval cranium description and its evolutionary implications (Amphibia: Anura: Hemiphractidae).

Hemiphractids have a singular mode of reproduction that involves maternal care. The Andean-endemic Gastrotheca marsupiata species group includes direct-developing and tadpole-bearing species, the latter trait being unique among Gastrotheca. Larval morphology has proven to be a valuable source of evidence to understand the taxonomy and evolution of frogs but remains understudied in Hemiphractids. Herein, we redescribe the larval cranium of G. espeletia, G. gracilis, G. marsupiata, G. peruana, G. pseustes, and G. riobambae, and describe those of G. aureomaculata, G. chrysosticta, G. litonedis, G. monticola and G. psychrophila. Additionally, based on the data gathered, we explore their phylogenetic significance, expanding the knowledge regarding Gastrotheca larval internal morphology. We suggest that the presence of the posterolateral process of crista parotica, the concave palatoquadrate, the quadratoorbital commissure, and the proximal commissures II and III are putative synapomorphies for Gastrotheca. Furthermore, we suggest the long pseudopterygoid process as a putative synapomorphy for Hemiphractyidae.